1. POLYCHLORINATED BIPHENYLS (PCBs) By Jenn Corpuz

2. PHYSICAL & CHEMICAL PROPERTIES C 12 H 10-x Cl x MP: 340-375 C Thin, lightly colored liquids to yellow or black waxy solids picture from: www.epa.govwww.epa.gov

3. PRODUCTION HISTORY Developed in 1929 Multiple congeners developed Used as a coolant for electrical equipment and as a plasticizer in paints, plastics and rubber products Banned by EPA in 1979 Products manufactured before 1979 are still releasing PCBs into the environment Most commonly known as: Aroclor, Phenoclor and Kanechlor

4. MODE OF ENTRY INTO AQUATIC ENVIRONMENT Run off Poorly maintained hazardous waste sites containing PCBs Burning of wastes in municipal or industrial incinerators

5. CHEMICAL REACTIVITY 209 known congeners (species) Most common: Aroclor, Phenoclors, Kaneochlors Most toxic: coplanar mono-orthosubstituted species Figure by Safe et. al.

6. CHEMICAL REACTIVITY (cont’d) Most species: insoluble in water Solubility decreases with increasing chlorination 0.01-0.0001ug/L Halflives: 3 wks -2 yrs (air) <6 yrs (aerobic soils/sediments) picture from: www.epa.govwww.epa.gov

7. TOXICITY TO AQUATIC LIFE Sediment bound Bioaccumulated and magnified through the food chain Rainbow Trout LC50= 0.32ug/L Laboratory Rats LD50= 1g/kg by weight Acute toxicity generally low Chronic toxicity gave results

8. TOXIC EFFECTS NOTED PCBs are known carcinogens Found to be highly associated with cancers in the immune, reproductive and endocrine systems Iipophilicity allows PCBs to live in animal’s tissues

9. MODE OF ENTRY Ingestion (most common) gills

10. MODE OF INTERACTION Induces AHH and binds to AhR Binds ARNT Leads to gene transcription PCBs have been linked to activation of oncogenes and inactivation of tumor suppressing genes

11. BIOCHEMICAL METABOLISM AND BREAKDOWN CYP1A and CYP1B are induced Resulting hydroxylated and methylsulfonyl PCB metabolites bind to DNA Highly chlorinated biphenyls are metabolized very slowly if at all Phase II (excretion) is unlikely Figure from Tabb et. al.

12. DEFENSE STRATEGIES FOR DETOXIFICATION For less chlorinated species: oxygenating chlorine sites  excretion through urine None for highly chlorinated species

13. BIBLIOGRAPHY www.epa.gov www.ehponline.org Hansen, Larry G. “Stepping Backward to Improve Assessment of PCB Congener Toxicities.” Environmental Health Perspectives. Volume 106. Feb 1998. McConnell, Ernest. “Comparitive Toxicity of PCBs and Related Compounds in Various Species of Animals.” Environmental Health Perspectives. Volume 60. 1985. 29-33. Neal, Robert A. “Mechanisms of the Biological Effects of PCBs, Polychlorinated Dibenzo-p-dioxins, and Polychlorinated Dibenzofurans in Experimental Animals.” Environmental Health Perspectives. Volume 60. 1985. 41-46. Safe, Stephen, Stelvin Bandiera, Tom Sawyer, Larry Robertson, Lorna Safe, Andrew Parkinson, Paul E. Thomas, Dene E. Ryan, Linda M. Reik, Wayne Levin, Mary Anne Denomme, and Toshio Fujita. “PCBs: Structure-Function Relationships and Mechanism of Action.” Environmental Health Perspectives. Volume 60. 1985. 47-56. Tabb, Michelle M., Vladyslav Kholodovych, Feliz Grun, Changcheng Zhou, William J. Welsh, and Bruce Blumberg. “ Highly Chlorinated PCBs inhibit the Human Xenobiotic Response Mediated by Steroid and Xenobiotic Receptor (SXR). Environmental Health Perspectives. Volume 112. 163-169.